Sound ranging computer



Sept. 16, 1952 R. 1.. DUNN 2,611,023

SOUND RANGING COMPUTER Filed Feb. 15, 1951 5 Sheets-Sheet 1 IN VEN TOR.I .l

RALPH L.DUNN FIG. I BY Af/arag/ Sept. 16, 1952 R. L. DUNN SOUND RANGINGCOMPUTER Filed Feb. 15, 1951 5 Sheets-Sheet 3 Q &I 17 w w 1 F111; Z77/43 Q a S; I 7 2 4 x 4 x l' 7 Q a .1 r0 g t) v I g g 5 g\ INVENTQR;

RALPH L.DUNN

Sept. 16, 1952 R. L. DUNN 2,611,023

souun HANGING COMPUTER Filed Feb. 15, 1951 s Sheets-Sheet 4 (D 7 g; m1/" /L- b N a [llllf LO 7 s2 4 LL 1/11 O m w m A n 7 i5 4 b O E m w aFER INVENTOR.

RALPH L. DUNN Patented Sept. 16, 1952 SOUND RANGING -COMPUTER Ralph; L.Dunn, Neptune, N;VJ., assignontozthe United States ofAmerica.aslrenresentedibythe, Secretaryof .the Army Application February15, 1951,- Serial No-.-21'1;173*' (Granted under the act of" March 3,188-3; as:-

amended April- 30, 1928;-370 G". 75-7)" 10,,Glaims.

The invention ldescribedlherein. may bemanufactured andused. by; oriforthe Goyernment ,for governmental lpiirposes, ,withoutlthelpayment of anyroyalty. thereorn Thislinvention relates. to, sound. location; and

more particularly to, ananalogue; computer. used in connection.withsoundwranging systems for automatically plotting the locations of la. sound sourceiby.utilizing relativerdifierences in arrival times ofthe sound at nrescribedlmicrophone locations ThepQOSiiJiQIlofiIa-soundi'sourcelmay, usually be determined ibyfmeasuring 1thedi'fierences in .time of garriyalioflsignals at each of. aseriesofmicrophones theclocations..ofQwhichareknown Erom theditierences; in varrival. time, it is possible, to determine groups ofhyperbolasflwhosel points of intersection may be utilized to. determinethe source: of thesound By; selecting any three known. microphone.positions,. these hyperbolas may be, constructedgby a close.approximation method involving-miscellaneous side, calculations,andnthenappliedl to thelsurfaceof aaplotting board... Qbviousl'y, this.is. a long, and tedious process. Furthermore, with change in microphone,positions, I a new set. of; hyperbolas would have. to be drawn In thepresent. invention, an electro-mechanical analogue ,of the.problemisiproduced and the solution. ion. the source of; sound.corresponding toithecdata. fromany threecselected microphones maybeaccomplished. automatically and" rapidly without .the need;for. anycalculation on. thepart ofltheoperatorh Itiis anlobject' of the presentinvention,. therefore, to provide an electromechanical analogue.computer. which automatically indicatesthe..bearingssota particularsound source; 7

His lanothenoliiectcof the invention to .provide an eiect'ro-mechanicallcomnutenwhich ,will .automatically andlrapidly indicate. theazimuth. and

ran e. positions ofia .sound'source. by utilizing the difierenceof timeof arrivalofthe sound, at preselected microphone locations.

In. accordance: with the present; invention there iswroyidedan"electro-mechanical analogue computer having means forsimulating the position .ofjthe .field microphones and? an indicatingdevice which may be positionedin" accordance with directcurrent:voltages proportional to-the relativeldifference of time arrivalatcorresponding microphones. Connected tothe indicating device" and"passing through" each simulated microphone location are a seriesof'thinwire tapes; orguide wires; each wire being attached to a springtensi'oned"retaining: drumto maintain. constant tension :onsaidwire.Means asso-- ciated' with each offjtheseretaining" drums are provided tosimultaneously; produce: the: direct current voltages whichiareproportionai'to. the

relative time difference of arrivals" atthe correspending microphonesThese voltages: are *then applied through :suita-ble amplifiers; to:range and azimuth. servo drivei motorsrwhich'position the indicatingdevice -to'simultaneonsly indicate both the. azimuth; and; range:locatiorrof; the sound,

drawings. in which:

source.

For a better; understanding: oi the invention together with other; andfurther objects-thereof, reference is had; to the: following descriptiontaken in connection with the: accompanying Fig. 1' is a plan ;view ofthe anai'oguecomputer;

Fig, 2', is averticahcross sectional'viewof the portion. above lineZE-ZofFig; 1 taken; substantially along line I-IT;

Fig, 3 is. avertical 1 cross sectional view" of the portion belowlineiZQZ'taken.substantially along line I'-I"0f.."1 fig 1 (Fig:'3-together:withFig; 2 form. one complete drawing);

Fig; 4 is anendi plan view" taken along line III-Iliof Fig, 712;

Eig. 5 isa vertical cross-sectional view taken substantially along lineIII III-goflilig: 1;

Big. 6 .is a,,perspective view showing the'd'etailed construction ofapotentiometer assembly embodied in my; invention; and

Fig, L7 illustrates. .theelectrical"conneotionsembodied in my inventionvReferring, now :to Figs. 1T5 oi'theid'rawings, the numeral Hidesignatesv a. flat. plotting surface which may; beconventionallymounted, onv a, suitable .base 12 by-means ofrsupportsl-MBychocsing: an. appropriate scale. factor; for example, 11inch=l000yards; a;,portion;0f.plotting; surface it):maygraphically'represcntrlirr miniature, a prescribed-"area of 'fieldioperationirrplane: polar or grid coordinates;- A: vertical; line: drawnthrough a datum, or-refe-rence;point; may' represen-t zero azimuth 01"any: suitable" reference azimuth and range maybe represented: by: aseries of"arcs=concentricabout the datumpoint. Thus, any solution pointon' the calibrated" portion ofsurface-ID may be-designated-in terms; ofrange and azimuth; For purposeof explanation, plotting-surface IO- maybe. considered as being divided; into a calibrated; or front:- plotting:section, and a rear:functionahsectionyuthe line; of demarcation being ahorizontal?v line drawn. arbitrarily on surface Ill a short distancebelow the datum point.

Mounted perpendicular to surface II and extending therethrough istubular shaft IE rotatably mounted inv fixed bearing' hous'ing ill; Thelongitudinalaxis of shaft I6 passes through the datum point and theupper end of said shaft is provided with annular flange 20. Mountedcoaxially Within tubular shaft I6 and radially spaced therefrom is solidcylindrical shaft 22. Shaft 22 extends through both ends of tubularshaft It, the upper end of shaft 22 being terminated by flange 24 towhich is secured discshaped pulley 26. The lower end of shaft 22. is

rotatably supported in position by bearing 28 which is affixed tohorizontal plate 39. Plate 36 is intermediate base I2 and surface I9 andmay lar retainer disc 36." Bythis arrangement it can on rotatable shaftI8, pinion 80 of the upper end of said shaft, a gear '82 on rotatableshaft 84, pinion 85 on the upper end of shaft 84, and gear 88 which iskeyed to tubular shaft I6. Plotting point carrier 52; is shownas'resolved" in range from servomotor "I2 by apinion 98 on the shaft ofsaid range motor, gear 92 on rotatable shaft 551, pinion 95 on the upperend of shaft 94, and gear 98 which is keyed to solid shaft 22.

A plotting point 91 which may be an inking type or an electric stylus,may be centrally mounted on theunderside of slidable pen carrier member5A. in the conventional-manner. If desired, plotting point 91 may besuspended during the transitory motion of plottin point carrier 52 bymeans of a solenoid 99 (Fig. 4) which is rigidly attached thereto. It isto be understood, of.

' "coursegthat the bottom of solenoid 99 is spaced readily be seen thatshafts I5 and .22 maybe rotated independently of each other.

Spaced from plotting surface I0 and parallel thereto is an elongatedplotting arm 38 provided with a central longitudinal'slotflfl whichextends for substantially the entire length ofsaid plotting arm. One endof said plottingarmis'rigidly rnounted to-annular lfiange .20 on shaftIii'by from surface iIl so that it does not impede the angular, movementof plotting arm 38.

Horizontally mounted on the rear functional section of'surfaceIIlposterior bearing housing I8 is a guide arm assembly I00 which providesthe means for relatively adjusting the miniature location of microphonesto correspond tothe actual relative locations of the microphone in thefield. Guide arm assembly I09 includes a series of spaced movable guidearms I62 which are parallel to and coplanar with' a' fixed} centerguide. arm I04. One end'of center guide arm I04 is rigidly mounted on avertical support post I06 which extends upwardly from the functionalsectionof surface I0. Thelongitudinalfaxis of post IE5 is meansof screwsdz and M (Fig. 5) in such a H manner that it 'is' free topivot aroundshaft 22.

' The other, end of said arm is-adapted to move freely in the calibratedsectio'njof surface III and is supported in position' 'by' anon-swiveling castor 56, the axle of thercontactwheels 48 being parallelto thelongitudinal axis of "plotting arm 38. Rotatably mounted at thefree end of arm 38 adjacent slot is guide pulley 50. If desired, meansmay be provided to position guide pulley 50 longitudinally along arm38.,

Mounted between the parallel edges of slot fill and in slidable contacttherewith, is plotting point carrier 52 comprising a'horizontal slidablepen carrier member 54 and a vertical wire support member 55 whichextends upwardly from said parallel to and .coplan-arwithf'the axis ofshaft 22 and is so positioned that the'other endof center arm. I04 issubstantially aligned with the datum, or reference, point and is spacedfrom the surface of pulley 25. Extending upwardly fromthe unattached endof center arm Iil iis an eyelet Iil'I which'ma'y be considered as theminiature representationof a preferred datum, or reference, microphonecorresponding to an actual microphone location in the field. Forillustrative purposes, the reference microphone location may bedesignated by the letter C.

On either side of fixed center guide arm its there are provided one ormore L-shaped movable guide arms I02. As stated above, the elongatedportions of said movable guide. arms'are parallel to and coplanarwith-center arm guide I04. Each of said movable arm guides is moun ed ona separate carriage I68 which is in sliding contact with spaced parallelguides H0 and H2 horizontally mounted on surface I0 between end slidablemember and is integral therewith. Slidable pen carrier member 54 isprovided with a threaded stud 58' to which is secured'ione endof a thinwire tape 60. The other-end of wire 60 is looped around guide pulley 551and is secured in the grooved periphery of pulley 26. Wire supportsection 56 is providedwith a central aperture 62 and a series ofthreaded studs 64, the purpose of which will hereinafterbe explained.

As shown in Fig. 5 tubular shaft I6 is rotatably driven through"suitable gearing 66 by servo drive motor 58, hereinafter referred to asthe azimuth motor. Solid shaft 22 is rotatably driven thru suitablegearing I0 byservo drive I2, here- .muth, of plotting-i,pointicarrier52, is shown as resolved in azimuth from motor 58 by pinion I4 on theshaft of the azimuth servomotor, gear I6 brackets H4 and H6. In theembodiment illustrated in the drawing, two movable guide arms areprovided on either-side of center guide arm I04, and for each movableguide arm IIlZthere is'a correspondingslidable carriage I88 which areidentical in construction.

Carriage I08 is provided with a central longitudinal slot I I8.to,accommodate a threaded longitudinal shaft I20 which is rotatablymounted between carriage endwalls i22'by means of suitable bearings. Oneendiofshaft I20 is terminated by manually rotatable knob I25. The short.or bent'portionof .L-shaped guide .arm I92 is mounted between the.walls of slot H8 and threadedly. engagesshaft IZt. By thisarrangementthe longitudinal position of guide arm I02 may be adjustedwithin the confines of slot H8 Y theother; Y

To adjust each guidearm I62 laterally in relaby' merely rotating knobI25 in one direction or tion, to rigid center arm I04, a transversethread edanerture: I 218 ls centrally'providedthe base of. carriage:I08? I70" engagethreaded shaft I33 which is centrally positioned-betweenspaced parallelguides'l I ll'and I Ij2transverse1to longitudinal shaft I26; The? transverse shafts I3 8- {are axially alignedj but" areindividually mounted in--bear inga I 32"so' thatthey may berotatedqindependently o-feach other." As 'showri,theouter transversesh'afts are-terminated by a manuallyrotat able knob'; I 34% Theinner" transverse shafts may be rotatedbymeans-o-f beveled-gears l atand +33, irrany suitable manner:

Mounted at the end of {the elongated portion ofea'ch guide'armandextending upwardly therefrom-" an eyelelr- I 91 which may be consideredas the miniature representation corresponding to the remaining actual-microphones the" field. Thus" it can readily be seen I that themi-niature representation of the microphone locations may be relativelyadjusted to correspond With-the-act dal-relative position of therophonesin -the field. Itis" to be understood; (ii-"course; that allfield-microphones are assumed to be located in the-same horizontalplane: Assn-own inFig l, the remaining-microphone locations aredesignated'as-A,B;-DandE.' I

Fivepotentiometer assemblies are provided, one-for each of the miniaturemicrophone locations. These potentiometer assemblies and the ipartsconnected to them' are-identic-al and this descriptiontherefore-applies-to each. Referring now to Figs.- 3' and fii'potentiometer assembly' I 3 comprises a conventional resistive element"-I39 a central rotating co-ntact arm I48 conventionally mounted' withincylindrical housings, M2. Asshown, resistive element I tllhiorms: anintegral part of cylindrical liousing: l 221 Said' housing is rotatablymountedlirr a horizontal planesbelcw surface 1 ill" by "meansof" shaftEda} which fixed to, the-base;- or lower plate; I or cyli ndr i-calhousing I 42, andbearing :Hiti Mountedon upper plate I50 of'saidcylindrical housing is the hub of gear L521. Gear i52-mesheswithacpinionul54 mounted'lon vertical shaftlI 55 whicl'i isrotatably mountedinnbearingszvlfia z Oneendof saidishaft: r

extends-upwardly through surface leiiandnis terminatedr by discI-lilceitime: inference dial: I58 which is::leyed .to shaiit'. i553;Contactzarrnii-dd::is afixc to one: endfoifiverfti: a1 (shelf t1tfifirwhich': e2:- tends's freely thlllli theihubuo-f gear 152. Theother: enclzof sh'aftatfiilxis coupl'ed to' colinear shaft" Ifif wiiichextends-upwardly through surface-Ill;

Mounted: horizontally" upon? the; end? of: shaft i fideistthezhub:OI'IBE retainingrdrunritfiswhich is conventionallyrproslidedwithtspolrese Extending upwardly "from: oneaofisaidi sp okes: andmounted horizontally thereomis:astwoewayithumb nutz'adjusting screwIulDL; The rim, 10.1 periphery :ofrreta-ining; drum use is aprovided-Jvith azgroovez- I 72;

which is :locatedjin substantially their sameuhorizontal. plane :as-thes' eyelets: 1'85! andaperturer 52 of plotting point. carrierrfi z,,Attaclredfjati one endtoi thumb :nut adjusting screw: l 'lfisisiaagpide wire I l id; which extends through? aw hole: I in .6 tached to--sliaft I64 and the otherendiorsald springis; rigidlyattached toauvertical post [88 extending-upwardly from surface-I8; As illustrated;the top-of post I 8D'is spaced from the underside of" retainingdrumjlfitn Preferably, post I80 maybe-positioned anterior shaft I65andaxi'ally spaced therefrom a distance substantia-lly equal to'theradi-us'of retainingdrum I55.

Spring-*HB maybe supporteol horizontally in positionby a disc: I84whichis mounted on shaft I64 on the-underside of drum I66. Retaining drumsassociated with microphone locations A, B, C; Hand-E are-located thesame distance above surface Ill; and'the shafts upon which they aremounted are linearly aligned. Thus for each miniature microphonerepresentation there is provided a potentiometer assembly, anassociatedtime difi erence dial, an associated retaining drum-andan'associated guide wire. It is to be assumed, of course, that theconstruction of corresponding elements are identical.

A narrow strip "of Plexiglas I82? is mounted just abovethe surface-ofthe time-difierence dials with engraved' lines to: provide a Zeroreference point 'for each dial. The graduated scales on,tlieedials-progress from zero in either'direction, one -h'alf"beingengraved in black, the other inred The-useoftwo colorsprovides a meansof discrimination-as towhether thetime of sound arrival at oneselectedmicrophon'e. is sooner-or later than the time arrival ofthe-sound. at anotherselected microphone.

Fig; 7 illustrates the: electrical components and connectionsemb'odiedin my: invention, A1, 13 C1, D1, 'and E1 indicate thepoteniiometers which are associatedwith miniature microphone locationsA,B, C, Dand E,'respectivcly as shown The resistive elements E39 areconnected in parallel across a suitable positive potential sovrceillil-lRotating contact-arms ME are connected' to corresponding terminals ofthree selector switches-1%; 206 and 2%. The ter- Initials of eachswitchare labeled A1, B1, C1, D1 and' Ei to indicate terminals which areassociatedwith the" contact-arm 0f correspondinc potentiometers. For"example, contact arm M9001 potentiometer Al is connected to terminal A1ofselector switches zt l, 2:!5 andZllB; respectively, contact armIeIl-of potentiometer B1 is connected to terminal 131 on' saidselectorswitches, etc.

Fol-convenience, selector switcheszili, Eiloand 208 may be respectivelydesignated as Azimuth, Referenceand Rance switches. The output ofReference switch 206 is applied as a reference "voltage to azimuth andrange servo amplifiers ZIB and 2I2; respectively. The. output of Azimuthswitch 2134 is applied only to'azimuthservo amplifier 218 and the;output of Range, switch ZFIS- is applied only to-range servo amplifier2.! 2. The constructionof these servo amplifiers are well known in theart and' operateconventionally to modu-late and amplify error voltagesaprlied thereto; The output of azimuth. servo amplifier 2'1 0 is appliedto azimuth servomotor '63 and the output'of ran-ge servo amplifierTI Zisapplied to range servomotor 12; The respective-mechanical connectionsof said motorsto plotting arm 38 'and plottingpoint carrier fidaredescribed"supra. Thus; bythe Azimuth" switch, one may selectthe-microphone to be user for comparative time tion for comparing theerror voltages corresponding to time arrivaldifferences with both theposition selected for thejrange channel; and the position selected forthe aziinuthchannel.

,Before the computer may be :placed into oporation, it is essential thatplottin Point carrier 52 be initially positioned, or indexed, inrelation to the microphone locations which are assumed to be positionedsubstantially along the same base line. This may be accomplished bypositioning plotting point 9'! at some prescribed plot, for example,6,000 yard range at-zero azimuth, and then milling out the resultingerror voltages between the center. microphone and the other microphonepositions by means cfthe corresponding time difference dial IBI'L-whichin turn-concontrols the relative position of the associatedpotentiometer resistors I39'with respect to contact arms I40. By thisarrangement plotting point 91 may ,initiallyjbe set at rest on thecenter line of the plotting surface which is directly in front of thecenter microphone position, and the length of theguide-Wire, or tape,i'Hi, for each microphone position may represent to scale,

the actual distance from any soundsource to the microphones in thefield-.Any slight discrepancy inerror voltage-maybe'adjusted by means ofthe tWo-waythumb nutpadjusting screw H which positions center contactarm I48 in relation to potentiometer resistor I39. Spring I18 actsagainst the movement of retaining drum I12 to maintain constant tensionon guide wire I74. With plotting point carrier 52 initially positionedas'described, supra, the computer is eration of this system, is that thesetting in of time differences on the bodies of the potentiometersestablishes voltage differences between the pairs of contact times ofeach of two pairs of potentiometers. These differences are applied toservo mechanisms which operate in such direction as to move the plottedpoint to a position where the voltage differences will be zero, whichcorresponds to the intersection of two separate hyperbolas. It is to beunderstood that the time differences may be set in manually or by anyother suitable means.

As previously explained, three microphones may be used at onetime. Thecombination of theiive inputs to selector switches 204-208 and the threeselected operative rotary contact arms I40 provide a total of 30 usablecombinations that may be set up. However, to operate properly,

. the selectedmicrophoncs must be such that the microphone selected as areference is disposed I between the other two selected microphoneposiother microphones must be on one side of D and the other must be onthe, other side of D, for example, microphone locations A and E.

.The information or intelligence to be set in the fred numerals on thecorresponding time difference dial. As explained above, by rotating maybe supplied in the form of graphic recordings of the times of arrival ofthe sound at various w microphone field positions. This information maybe manually introduced as anferror voltage at the respective,potentiometer assemblisby means of the'associated time difference dialI66.

As mentioned: above, a suitable microphone may be selected as areference and the associated time'diiference dial lfiu positioned at thezero reference point provided therefor on Plexiglas I82. The times ofarrival of a sound source at the two other selected microphones, withrespect to the reference microphone may be designated as an early timeand a late time, depending upon the relative distance of the source ofsound from the microphones.

The late time is introduced to one of the selected microphone positionsby means of the black numerals on the associated time difference dial.The early time is introduced tothc other selected microphone position bymeans of the dials I60, the associated potentiometer bodies I42 arerotated relative to rotating contact arm I40, thus setting up errorvoltages withrespect to the selected reference microphone location. Oneerror. voltage is applied to range servomotor I2'through Range switch288 and range servo amplifier 2H), where it is compared to the referencevoltage by'm'eans ofIReference switch 206. Similarly, the other errorvoltage is com pared to the output of the voltage corresponding to thereference microphone in azimuth servo amplifier 2 I 2, and the output ofsaid servo amplifier is fed to azimuth servomotor 68. The servomotorsoperate in such a manner as to effectively cancel out the error voltage.In other words,

the'error voltages are nulled out and the plotting point comes to restat a plot representing the in-,

tersection of twoseparate hyperbolas.

'Azimuth servomotor 68 rotates shaft 34 through gear mechanism 68andrange servomotor 12 rotates shaft 22 through gear mechanism 10'. Ashereinbefore explained, shaft 34 controls the angular position ofplotting arm 33 and shaft 22 controls the position of the pen carrieralong longitudinal slot 40. As the plotting point carrier is positionedby the servomotor drives, the center contact arms I40 of the selectedpotentiometers are actuated by the movement ;of the guide wires I14until the error voltages are nulled out. At this instant, plotting point91 will reston the solution point corresponding to the time differencesas represented at the selected wires is maintained constant by theaction of spring I18 against the movement of retaining Similarly, anythree other microphones may be operated in the same manner to skilled inthe art that various changes and *modiflcations may be made thereinwithout departing from the invention, and it is, therefore, aimed in Ithe appended claims to cover all such changes and scope of theinvention.

What is claimed is: I '1. A sound locating device fcriuse. with" a andmodifications as fall within the true spirit sound ranging systemwherein a plurality of microphones are employed in a prescribed held Thetensionof the guide ,9 of operation to record the relative arrivaltimesof a source of sound-comprising aflatrsur'face, a portion of saidsurface being calibrated to ;reproduce said field of operationinminiature and to scale, said calibrated surface'havingaprescribed datumpoint, .means mounted 'on said calibrated surface for reproducing \inminiature and to scale the locationof-thelfield microphones relative tosaid datum point anielongated:plotting arm operable on sa idcalibrate'dlsurface and adapted to pivot about. said datum. point, aplotting point carrier slidably .mounted on said plotting arm, meansassociated withreachiofksaid reproduced microphone l'locat'ions .i'for lindicating the difference in arrival times-iota particular sound sourceat each reproduced microphone location with respect to a,prescribe'dislected microphone location, and i means dr'ivenlyconnectedto said time difference indicating-means for simultaneouslypivoting said .plotting arm about said datum point and positioning .saidplotting point carrier alcngsaid arm.

2. A sound locating devicefor use withasound ranging system whereinza,pl-urality oflmicrophones are employed ina prescribedfield of operationto record the-relative arrival times-of a source of sound, comprising aflat surfaceaportion of saidsurface being calibrated to reproduce saidfield of operation: miniature-and to scale, said calibrated surfacehaving a, prescribed datum point, means mounted on :said calibratedsurface for reproducing in miniature and to scale the location ofttherfield microphones relative to said datum point, an elongatedplotting arm operable on said calibrated-isurfaceeand adapted to pivotabout said datum point,-. a plotting point carrier slidably mountedalong the longitudinal axis of said plotting-armmeans for indicating thediiference in -arrival'times of :a particular sound source ateach-microphone locationwith respect to a prescribed selected microphoneloca-- tion, means for selecting 'twoof the -ti me- -arrival differencesfor said ;particular sound source, means for converting :sa-idsselectedtime differences to corresponding error voltagesrhaving the sameproportion relative to each other aszsaid selected time differences, andmeansresponsive to said error voltages for pivoting saidplotting armabout said datum point and simultaneously positioning said plottingpoint carrier along the longitudinal axis of said plotting arm.

3. A sound locating device for use with a sound ranging system wherein aplurality of microphones are employed'lin aprescribed field of operationto record'the relativearrival times of a source of sound, comprising-aflatsurface, a portion of said surface beingcali-brated toreproduce saidfield of operation inminiature and to scale, said calibrated surfacehaving a prescribed datum point, means mounted ion said calibratedsurface for reproducingin miniature and to scale the locationofthe fieldmicrophones relative to said datum'point, an elongated :plotting armoperable on-saidcalibrated-surface and adapted to pivot about-saiddatum: point, iaiplotting point carrierslidably mounted along thelongitudinal axis of said elongated plotting arm, means for indicatingthe difference in arrival times of a particular sound source-atleachreproduced microphone location -With .respectto a prescribed selectedmicrophone location, means for selecting two of said timearrivaldifferences for said particular sound .source', means'for convertingsaid selected time differences to corre- M spondingerror voltageshaving.thefsamejproportion relative to each other as said selectedtime.difierences, 'a first servomotor responsive to one of said errorvoltages and QliVGIHY'COIlHCG-BBG to said jplotting arm, "d second"servomotor re- 5 sponsive'to'the "other of said errorvoltages anddrivenly' connected tosai'd'plotting point carrier, and .meansresponsive to the combined movement'ofsaid plotting arm andsaidplottingpoint ..carrier'for;nullingoutz-saiderror voltages Where- Zbysaidcarrierissubstantiallypositioned at the location "of said particular soundsource.

4. A "sound locating "device for use "with -*a soundrangingsystem'whereinraplurality-of rn-icrophones"are'employed'inaprescribed field of 5 operation"torecord "the-relative arrival times of"a "source *of sound, "comprising a, fiat 1 surface, a p'loifion "of'sai'df'surfac'e being'calibrated to reproduoe"'said new or operationinminiatureand 'fto ."soale, =sa'r'd "calibrated surface having a pre-'scribed datum :"point, means mounted on "said fca'librate'd't surfaceforireproducing in miniature "and to scale'the location of the fieldmicrophones relative to said "datum point, an elongated plottingarm'operab'leton said calibrated surface and fadaptedtopivotaboutsaiddatum; point, a plottingpointcarrier slidably mountedalong the longitudinal axis of'said elongated plotting arm, "means "forindicating the difference in arrival times "of a "particularsoundrsource "at" each reproduced microphone location with respect to aprescribed 'se'lected"microphone location, "means 'for' selecting two ofsaid"time arrivaldifferences for said particular sound source;means forconverting said "selected time "differences to corresponding errorvoltages having th'e same "propor tionirelative Ito teachotherfias saidselected 1 time -drfferencesxmeans 'responsiveito said error voltages"for 'pivotin'g said plotting arm ab out said "datum point andsimultaneously"positioning said 40 plotting-pointcarrier*alongthe''longitudinalraxis of said 'plotting arm, "and means "responsive to 'thelongitudinal movement of said plottiilg point carrier to null outsaiderrorvoltages'whercby said plotting-point carrieris substantially"posi- 'ti-on'ed at the location'of said particular sound source.

5. "A sound locating "device for use with a "sound ranging systemwherein a "plurality of microphones "are employed 'in' a prescribedfield of operationto record the relative "arrival times of asouroe ofsound, comprisinga flat surface, a portion "of said surface beingcalibrated "to "reproduce said nemof operation 'in-miniatuream toscale,said "calibratedsurface having"a prescribed "datum point, 'means"mounted on "said calibrated surface for reproducing in miniature "andto scale the location "of the' fieldmicrophones relative tosaid datumpoint, "an" elongated pl'otting arm operable onsa'id" calibrated'srurfaceand adapted to pivot'aboutsaiddatum, point, a plotting pointcarrier slidably "mounted -along the longitudinal axis of said elongatedarm, 11163115 foriin'dicating" thedi-fferencepin arrival'times'of' aparticularsound "source" at each reproduced'rni- *crophone locationwith'respectto a1 prescri'o ed selected microphone location, means "for-selecting two of s'aid time"arrival-differences.for' said particula'r-sou-nd source,means 1 for converting; said selected timediiiserenc'es to corresponding error *voltages having thesame-proportionrelative to "each othenas said selected time differences, I

plotting arm carrier along said plotting arm,

, and means responsive to the movement of said crophones are employed ina prescribed field of 7 operation to record the relative arrival timesof a source of sound, comprising a flat surface, a portion of saidsurface being calibrated to reproduce said field of operationinminiature and to scale, said calibrated surface having a prescribeddatum .point, means mounted on said calibrated surface for reproducingin miniature and to scale the location of the field microphones, anelongated plotting arm operable on said calibrated surface and adaptedto pivot aboutsaid datum point, a plotting point carrier slidablymounted alongthe longitudinal axis of said elongated plotting arm, meansfor selecting one of said reproduced microphone locations as a referencecorresponding to zero arrival time of a particular sound source, meansassociated with each of the reproduced microphone locations forconverting the respective difference in arrival times of. saidparticular sound source at said remaining microphone locations tocorresponding error voltages having the same proportion relative to eachother as said time differences, means for selecting two of said errorvoltages, means responsive to one of said error vo1t ages for pivotingsaid-plotting arm about said datum point, means responsive to the otherof said error voltages for longitudinally positioning said plottingpoint carrier ,along said plotting arm and means responsive to themovement of said plotting point carrier tovnull out said error voltageswhereby said plotting point carrier is substantially positioned at thelocation of said particular sound source.

'7. A sound locating device associated with a sound ranging systemwherein a plurality of microphones are employed in a prescribed field ofoperation to record the relative arrival times of a source ofsound,,comprising a fiat surface, a portion of said surface beingcalibrated to reproduce said field of operation in miniature and toscale, said calibrated surface having a prescribed datum point, meansmounted on said calibrated surface for reproducing in miniature and toscale the location of the field microphones, an elongated plotting armoperable on said calibrated surface and adapted to pivot about saiddatum point, a plotting point carrier slidably mounted along thelongitudinal axis of said elongated plotting arm, means for selectingone of said reproduced microphone locations as a reference correspondingto zero arrival time of a particular sound source, means associated witheach of the reproduced microphone locations for converting therespective relative difference in arrival times of said particularsound'sourc'e at said remaining microphone locations to correspondingerror voltage-shaving the same proportion relative to each other as saidtime differences, means for selecting two of said error voltages, afirst servomotor responsive to said first error voltage, a second i2.plotting arm, and means responsive to'the movement of said plottingpoint carrierv to null out said error voltages whereby said plottingpoint carrier is substantially positioned at the'location of saidparticular sound source. v v

' 8. A sound locating device for use witha sound ranging system whereina pluralityv of microphones are employedin a prescribed field of0-peration to record the relative arrival times of a source of sound,comprising a fiat-surface, a'portion of said surface being calibrated toreproduce said field of operation in miniature and to scale,

said calibrated surface having a prescribed datum I point, means mountedon said calibrated surface for reproducing in miniature and to scale thelocation of the field microphones relative to said datum point,an-e-longated plotting arm operable on said calibrated surface andadapted to pivot about said datum point, a plotting point carrierferences in arrival times of a particularsound source at each microphonelocation with respect to a prescribed microphone location whereby errorvoltages areinitiated between respective resistive elements-and contactarmspsaid error voltages'having the same proportion relaciveto eachother as said time differences, means for selectingtwo of saidpotentiometer error voltages, and means responsive to one of saidselected error voltages for pivoting said plotting arm about said datumpoint to indicate the azimuth of saidparticular sound source, meansresponsive to the other of said selected error voltages forlongitudinally positioning said plotting point carrier along saidplotting arm to indicate the range'of said particular sound source, saidguide wires rotating the contact arms of the selected potentiometers insuch'a manner as to null out'said selected error voltages. r

9. A sound locating device for use with a sound ranging system wherein aplurality of microphones are employed in a prescribed field of operationto record the relative arrival times of a source of sound, comprising afiat surface, a portion of said surfrace being calibrated to reproducesaid field of operation in miniature and tosurface for reproducing inminiature and to scale the location of thefield microphones relative tosaid datum point, an elongated plotting arm op erable' on saidcalibrated surface and adapted to pivot about said datumpoint, aplotting point carrier slidably mounted onsaid plotting arm, a pluralityof potentiometer-s corresponding in number to the number of fieldmicrophones, each of said potentiometers having a relativelyrotatablec-ontact arm and resistiveeleme'nt;adirect currentpotentialsource, said resistive element being in electrical'parallel connectionacross said voltage source, a discrete guide wire extending through eachreproduced jmicrophone location and connecting eacl'iof said contactarms to-said plottin point carrier, means drivenlv connected to each 01'saidresistive elements for indicating the differences in arrival timesof a particular sound source at each microphone location with respect toa prescribed microphone location whereby error voltages are initiatedbetween respective resistive elements and contact arms, said errorvoltages having the same proportion rel-ative to each other as said timedifferences, means for selecting two of said potentiometer errorvoltages, a first servomotor responsive to one of said error voltagesand drivenly connected to said plotting point arm to pivot said armabout said datum point, a second servomotor responsive to the other ofsaid selected error voltages and drivenly connected to said plotting|point carrier to longitudinally position said plotting point carrieralong said arm, said guide wires being responsive to the combinedmovement of said carrier and said arm to null out said error voltageswhereby said carrier is substantially positioned at the location of saidparticular soundsource.

10. The invention according to claim 9, where in means are provided formaintaining constant 10 tension on said guide wires.

RALPH L. DUNN.

No references cited.

